Codeforces 1090B - LaTeX Expert - [字符串模拟][2018-2019 Russia Open High School Programming Contest Problem B]

题目链接：https://codeforces.com/contest/1090/problem/B

Examples
standard input

The most famous characters of Pushkin’s works are Onegin \cite{onegin},
Dubrovsky \cite{dubrovsky} and Tsar Saltan \cite{saltan}.
\begin{thebibliography}{99}
\bibitem{saltan} A.S.Pushkin. The Tale of Tsar Saltan. 1832.
\bibitem{onegin} A.S.Pushkin. Eugene Onegin. 1831.
\bibitem{dubrovsky} A.S.Pushkin. Dubrovsky. 1841.
\end{thebibliography}

standard output

Incorrect
\begin{thebibliography}{99}
\bibitem{onegin} A.S.Pushkin. Eugene Onegin. 1831.
\bibitem{dubrovsky} A.S.Pushkin. Dubrovsky. 1841.
\bibitem{saltan} A.S.Pushkin. The Tale of Tsar Saltan. 1832.
\end{thebibliography}

standard input

The most famous characters of Pushkin’s works are Onegin \cite{onegin},
Dubrovsky \cite{dubrovsky} and Tsar Saltan \cite{saltan}.
\begin{thebibliography}{99}
\bibitem{onegin} A.S.Pushkin. Eugene Onegin. 1831.
\bibitem{dubrovsky} A.S.Pushkin. Dubrovsky. 1841.
\bibitem{saltan} A.S.Pushkin. The Tale of Tsar Saltan. 1832.
\end{thebibliography}

standard output

Correct

题意：

文章末尾这个参考文献的顺序可能是错乱的，需要你修正一下。

题解：

就是考察字符串输入输出以及其他一些操作的，用map<string,int>哈希一下参考文献的标识，然后老老实实模拟就行了。

AC代码：

#include<bits/stdc++.h>
using namespace std;

struct Cite{
    int idx;
    string str;
    Cite(){}
    Cite(int _i,const string& s) {
        idx=_i, str=s;
    }
    bool operator<(const Cite& oth)const {
        return idx<oth.idx;
    }
};
vector<Cite> cites;

int tot;
map<string,int> mp;

void Find(const string& s)
{
    int pos,beg=0;
    while((pos=s.find("\\cite{",beg))!=-1)
    {
        string res;
        for(beg=pos+6;beg<s.size() && s[beg]!='}';beg++) res+=s[beg];
        mp[res]=++tot;
    }
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);

    string str;
    bool END=0;
    tot=0; mp.clear();
    while(getline(cin,str))
    {
        if(str=="\\begin{thebibliography}{99}") {END=1;continue;}
        if(str=="\\end{thebibliography}") break;
        if(!END) Find(str);
        else
        {
            int pos=str.find("\\bibitem{");
            string res;
            for(pos+=9;pos<str.size() && str[pos]!='}';pos++) res+=str[pos];
            cites.push_back(Cite(mp[res],str));
        }
    }

    bool CORRECT=1;
    for(int i=0;i<cites.size();i++) if(cites[i].idx!=i+1) CORRECT=0;
    if(CORRECT) cout<<"Correct\n";
    else
    {
        cout<<"Incorrect\n";
        sort(cites.begin(),cites.end());
        cout<<"\\begin{thebibliography}{99}\n";
        for(int i=0;i<cites.size();i++) cout<<cites[i].str<<'\n';
        cout<<"\\end{thebibliography}\n";
    }
}